Process of producing cellulose acetate yarn



tile winding devices.

'1 respects.

UNiTED STATES PROCESS 0F PRODUCING CELLULOSE ACETATE YARN PATENT: OFFICE Camille Dreyfua New York, N. Y., and William Whitehead, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application April 21, 1928 Serial No. 271,974

3 Claims. (01. 18-54) This invention relates to the preparation of yarnsor films containing cellulose acetate from solutions containing the same.

An object of our invention is to prepare yarns from' cellulose acetate by spinning solutions of cellulose acetate in a solvent mixture containing cellulose acetate, a solvent therefor and methyl alcohol. Other objects of our invention will appear from the following detailed description.

In the spinning of yarns containing cellulose acetate by the dry spinning method, solutions or dopes of the cellulose acetate in a solvent are forced through fine orifices positioned in a device known as a jet orspinneret. The fine threads of the solutions thus extruded are subjected to the drying action of air at suitable temperatures, whereupon the solvent is driven off and solid filaments are formed. These filaments are gathered up and wound up by any of the usual tex- In this winding the filaments under formation (i. e. in the state of transition from solution to filament) are drawn out by the winding devices to a length greater than that which would be obtained by the filaments 'jif allowed to dry without being wound up. It is highly desirable to draw these filaments to as fine a denier as possible, as yarns thus derived are much softer and more pliable than yarns not so drawn out, and are also superior in other We have found that if methyl alcohol is added to the solvent mixture used in the preparation of' the solution or dopes from which the cellulose acetate yarn is spun, the capability of the spinning solution of being drawn out is greatly improved. Although methyl alcohol is not a solvent for the cellulose acetate; when added to a films are made from a solution of cellulose acetate in a solvent that contains methyl alcohol. The cellulose acetate used in our invention'may or may not be soluble in'acetone, but we prefer to use an acetone soluble cellulose acetate having an acetyl value of 52.5% to 56% and preferably 'T54.-.5%, but this invention is not limited to the use of such cellulose'acetate.

While we do not limit ourselves to a specific solvent to be used in our process, we have found that the use of acetone as the solvent gives excellent results. The amount of methyl alcohol that may be used may be varied in accordance with the particular requirements of the operator in accordance with the data given below.

By way of example, the following characteristics are pointed out of solutions containing varying amounts of acetone and methyl alcohol of a cellulose. acetate that has an acetyl value of 54.5% and which is soluble in acetone, and which is not soluble in chloroform but which absorbs chloroform without becoming sticky or plastic. The cellulose acetate is dried under vacuum to a moisture content of less than 1%. The acetone' used has a boiling point of 56 C. and the methyl alcohol has a boiling point of 64.5 C. A solution is formed containing 25.7% of cellulose acetate.

Solvent ltnixtutre con- Viscosiitty detersis ing 0 mine y time in seconds taken gg g by a 7/32 in. steel p filament ball to fall methyl f if 552121 512 acetone co umn o t e 1 alcohol solution at Spun The spinning is performed by extrusion through a circular jet orifice of 0.08 mm. in diameter The definition of denier is the weight of 9000 meters of the filament in grams. The spinning temperature is preferably between 50 and 65 C.

It will be seen that with the presence of 2% to 5% of methyl alcohol and 98% to of acetone in the solvent mixture, excellent drawdown properties of the spinning solution result, and we therefore prefer to use these proportions.

-While this invention has been described specifically with respect to the use of cellulose acetate, it may be applied to such cellulose esters such as cellulose formate, cellulose'propionate, or cellulose butyrate that display the same properties as the cellulose acetate described above.

It is to be understood that the'foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from'the spirit of this invention.

Having described our invention, .what we claim and desire to secure by Letters Patent is:

1. Method of producing yarns comprising making a solution of an acetone soluble cellulose acea tate in a solvent mixture comprising acetone and methylalcohol, and then dry spinning said solution.

2. Method of producing yarns comprising dis- 5 solving an acetone soluble cellulose acetate in a solvent mixture comprising between 95% to 98% of acetone and 5% to 2% of methyl alcohol, an

then dry spinning the same. 

